Internal combustion engine

摘要

To facilitate assembly of a cam chain and enhance an effect of separating oil mist from a blow-by gas introduced into a breather chamber in an internal combustion engine including: a cam drive sprocket provided to a crankshaft; a cam driven sprocket provided to a cam shaft rotatably supported by a cylinder head; a cam chain chamber for moving an endless cam chain stretched around the cam drive sprocket and the cam driven sprocket, which extends from the crankcase to the cylinder block and further to the cylinder head; and a breather chamber communicating with an upper portion of the cam chain chamber on the crankcase side and defined in the crankcase. A protruding wall 104 is provided in a crankcase 20 in the form of protruding to a cam chain 93 side, the wall being positioned at an inlet 103 that opens to a cam chain chamber 94 of a breather chamber 101 and crossing a movement direction of the cam chain 93.